US5447596A - Apparatus for producing semiconductor wafers - Google Patents

Abstract

An apparatus for separating a wafer from a support plate, to which the wafer is bonded with a thermally softened adhesive, includes an upper plate having opposite upper and lower surfaces and a plurality of holes having apertures at the lower surface through which air is evacuated to hold the support plate to the lower surface; a lower plate having opposite upper and lower surfaces and a plurality of holes having apertures at the upper surface through which air is evacuated to hold the wafer to the upper surface; a heater for softening the thermally softened adhesive embedded in at least one of the upper and lower plates; a robot arm for moving the upper plate in vertical and horizontal directions; and a shaft for rotatably connecting the upper plate to the robot arm. In operation, after the adhesive connecting the wafer and the support plate is softened by the heater, the robot arm moves the upper plate upward while rotating or turning the upper plate, whereby the support plate is separated from the wafer. Therefore, the wafer is prevented from cracking and breaking, whereby the production yield is increased, resulting in a reduction in the cost of the device.

Description

FIELD OF THE INVENTION

The present invention relates to an apparatus for producing semiconductor wafers and, more particularly, to an apparatus for separating a wafer from a support plate which is adhered to the wafer with a thermally softened adhesive to increase the strength of the wafer during rear surface treatment of the wafer.

BACKGROUND OF THE INVENTION

FIG. 19 is a sectional view illustrating a conventional apparatus for separating a wafer from a support substrate. FIG. 20 is a sectional view of a wafer adhered to a support plate.

In FIG. 20, awafer 1 is adhered to asupport plate 2, such as a glass plate, with a thermally softenedadhesive 209, such as wax. Hereinafter, thewafer 1 with theglass plate 2 is called awork 20.Reference numeral 3 designates a metal projection formed at the periphery of the boundary between thewafer 1 and theglass plate 2 due to vapor-deposition or plating.

In FIG. 19, thework 20 is interposed between alower plate 201 and anupper plate 204. Alower plate 201 includes anupper surface 201a in contact with thewafer 1 of thework 20 and a plurality ofopenings 201b at theupper surface 201a. Theseopenings 201b are connected to atube 202, and thetube 202 is connected to an external vacuum pump (not shown). Since air is evacuated through theopenings 201b by the vacuum pump, thewafer 1 is held against theupper surface 201a of thelower plate 201. Aheater 203 is buried in thelower plate 201.

The structure of theupper plate 204 is identical to thelower plate 201. That is, theupper plate 204 includes alower surface 204a in contact with theglass plate 2 of thework 20 and a plurality ofopenings 204b at thelower surface 204a. Theseopenings 204b are connected to atube 205, and thetube 205 is connected to an external vacuum pump (not shown). Since air is evacuated through theopenings 204b by the vacuum pump, theglass plate 2 is held against thelower surface 204a of theupper plate 204. Aheater 206 is buried in theupper plate 204. Furthermore, an end of ashaft 207 is fixed to the upper surface of theupper plate 204, and the other end is fixed to ahandle 208.

A description is given of the operation.

Initially, a wafer 1 (diameter: 76 mm, thickness: 600 μm) having a front surface on which circuit elements are disposed is adhered to aglass plate 2 usingwax 209 so that the front surface of thewafer 1 is in contact with theglass plate 2, whereby thewafer 1 is reinforced. Then, thewafer 1 is ground from the rear surface until the thickness of the wafer is several microns to several hundreds of microns. Thereafter, a metal pattern is formed on the rear surface of thewafer 1 by plating or the like. In the plating process, ametal projection 3 is grown at the periphery of the contact part between thewafer 1 and theglass plate 2 as shown in FIG. 20.

After the process on the rear surface of thewafer 1, an operator puts thework 20 on theupper surface 201a of thelower plate 201 by hand. Since air is evacuated through theopenings 201b of thelower plate 201 by the vacuum pump, thewafer 1 is fixed to thesurface 201a. At the same time, thelower plate 201 is heated by theheater 203.

Then, the operator takes thehandle 208 of theupper plate 204 and puts theupper plate 204 on theglass plate 2 of thework 20. Since air is evacuated through theopenings 204b of theupper plate 204, thesupport plate 2 is held against thelower surface 204a of theupper plate 204. Theupper plate 204 is heated by theheater 206.

Thework 20 is heated for a prescribed time to soften thewax 209 between thewafer 1 and theglass plate 2 and, thereafter, thehandle 208 is moved in the direction indicated by the arrow in FIG. 19, whereby theglass plate 2 is separated from thewafer 1. Then, the operator manually disconnect thewafer 1 and theglass plate 2 from thelower plate 201 and theupper plate 204, respectively, followed by subsequent process steps.

In the above-described conventional apparatus, when theglass plate 2 is separated from thewafer 1, thewafer 1 is flawed or cracked due to themetal projection 3, whereby the wafer is broken in the wafer separating step or in the subsequent steps, such as a wafer washing step.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatus for separating a wafer from a support plate that prevents the wafer from cracking or breaking when it is separated from the support plate, thereby increasing production yield and reducing the cost of the device.

It is another object of the present invention to automate such an apparatus.

Other objects and advantages of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific embodiment are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

According to a first aspect of the present invention, an apparatus for separating a wafer from a support plate, the wafter being bonded to the support plate by a thermally softened adhesive, comprises an upper plate having opposite upper and lower surfaces and a plurality of holes having apertures at the lower surface through which air is evacuated to hold support plate to the lower surface; a lower plate having opposite upper and lower surfaces and a plurality of holes having apertures at the upper surface through which air is evacuated to hold the wafer to the upper surface; a heater for softening the thermally softened adhesive, embedded in at least one of the upper and lower plates; a robot arm for moving the upper plate in vertical and horizontal directions; and a shaft for rotatably connecting the upper plate to the robot arm. In operation, after the thermally softened adhesive connecting the wafer and the support plate is softened by the heater, the robot arm moves the upper plate upward while rotating or turning the upper plate, whereby the support plate is separated from the wafer. Therefore, the wafer is prevented from cracking and breaking, whereby the production yield is increased, resulting in a reduction in the cost of the device. In addition, since the upper plate is supported and controlled by the robot arm, the separation is easily carried out with high reliability.

According to a second aspect of the present invention, the apparatus further includes means for absorbing shock generated when the work, i.e., the wafer with the support plate, held against the lower surface of the upper plate is put on the upper surface of the lower plate. Therefore, the wafer is prevented from cracking.

According to a third aspect of the present invention, the apparatus further includes means for holding the support plate to the lower surface of the upper plate by pressing the support plate against the lower surface. Therefore, when the upper plate is moved upward by the robot arm, the peripheral portion of the support plate is bent upward, and the support plate is gradually separated from the periphery of the wafer, whereby the separation is facilitated.

According to a fourth aspect of the present invention, the apparatus further includes means for pulling the lower plate downward in the vertical direction, disposed on the lower surface of the lower plate. The tensile force applied to the lower plate is a little lower than the attraction of the upper and lower plates. Therefore, the separation is carried out with high stability.

According to a fifth aspect of the present invention, the upper plate has a convex lower surface. Therefore, the support plate is easily separated from the wafer.

According to a sixth aspect of the present invention, the upper plate comprises a central disc part fixed to the shaft and a peripheral annular part moving in the vertical direction. The peripheral annular part is moved upward prior to the central disc part, so that the support plate is separated from the periphery of the wafer.

According to a seventh aspect of the present invention, the apparatus further includes a nozzle for applying a solution that dissolves the thermally softened adhesive at the boundary between the wafer and the support plate. Therefore, the removal of the adhesive is encouraged, whereby the separation is facilitated.

According to an eighth aspect of the present invention, the apparatus is put in a container filled with a solution that dissolves the thermally softened adhesive. Further, the container is hermetically sealed and the pressure in the container is increased. Therefore, the permeation of the solution into the adhesive is increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an apparatus for separating a wafer from a support plate in accordance with a first embodiment of the present invention.

FIG. 2 is a sectional view of the apparatus shown in FIG. 1.

FIGS. 3(a) to 3(c) are sectional views for explaining the operation of the apparatus shown in FIG. 1.

FIG. 4 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a second embodiment of the present invention.

FIG. 5 is a perspective view illustrating a mechanism for holding a wafer included in the apparatus shown in FIG. 4.

FIGS. 6(a) and 6(b) are sectional views for explaining the operation of the wafer holding mechanism of FIG. 5.

FIG. 7 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a third embodiment of the present invention.

FIG. 8 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a fourth embodiment of the present invention.

FIG. 9 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a fifth embodiment of the present invention.

FIGS. 10(a) and 10(b) are sectional views illustrating an apparatus for separating a wafer from a support plate in accordance with a sixth embodiment of the present invention.

FIGS. 11(a) and 11(b) are sectional views illustrating an apparatus for separating a wafer from a support plate in accordance with a seventh embodiment of the present invention.

FIG. 12 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with an eighth embodiment of the present invention.

FIGS. 13(a) and 13(b) are perspective views illustrating an upper plate included in the apparatus of FIG. 12.

FIG. 14 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a ninth embodiment of the present invention.

FIGS. 15(a) to 15(c) are diagrams for explaining the operation of an upper plate included in the apparatus shown in FIG. 14.

FIG. 16 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a tenth embodiment of the present invention.

FIG. 17 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with an eleventh embodiment of the present invention.

FIG. 18 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a twelfth embodiment of the present invention.

FIG. 19 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with the prior art.

FIG. 20 is a sectional view illustrating a work in a state where prescribed process steps for the wafer and the support plate are completed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 are a perspective view and a sectional view, respectively, illustrating an apparatus for separating a wafer from a support plate in accordance with a first embodiment of the present invention. FIGS. 3(a)-3(c) are sectional views for explaining the operation of the apparatus shown in FIGS. 1 and 2. In this first embodiment, alower disc plate 4 includes anupper surface 4a in contact with thewafer 1 of thework 20, at least two concentricannular grooves 4b connected to each other in thelower plate 4, and atube 5 connecting theannular grooves 4b to an external vacuum pump (not shown). Air is evacuated through theannular grooves 4b and thetube 5 by the vacuum pump, so that thewafer 1 is held against theupper surface 4a of thelower plate 4. Thelower plate 4 further includes a plurality of through,holes 4c in whichcartridge heaters 6 are inserted.

Fourguide rods 7 are fixed to the lower surface of thelower plate 4 at equal intervals in a direction perpendicular to the lower surface. Theserods 7 are inserted in cylindrical andhollow holders 9 which are fixed to abase 10. Foursprings 8 are disposed between thelower plate 4 and therespective holders 9. Thelower plate 4 is supported by the elasticity of thesprings 8, whereby any mechanical shock applied to thelower plate 4 when the work is mounted on theupper surface 4a is reduced.

Anupper plate 11 has the same structure as the above-describedlower plate 4. That is, theupper plate 11 includes alower surface 11a in contact with theglass plate 2 of thework 20, at least two concentricannular grooves 11b connected to each other in theupper plate 11, and atube 12 connecting theannular grooves 11b to an external vacuum pump (not shown). Air is evacuated through theannular grooves 11b and thetube 12 by the vacuum pump, so that thework 20 is held against thelower surface 11a of theupper plate 11. Theupper plate 11 further includes a plurality of through-holes 11c in whichcartridge heaters 13 are inserted. An end of ashaft 14 is fixed to the center of the upper surface of theupper plate 11 while the other end is connected to arobot arm 16 via acoupling 15, so that theupper plate 11 can be vertically and rotatably moved by therobot arm 16.

A description is given of the operation.

When awork 20 comprising awafer 1 and aglass plate 2 is taken out from a cassette (not shown), theupper plate 11 is moved to a position above thework 20 by the robot arm 16 (FIG. 3(a)). Then, therobot arm 16 is moved downward until thelower surface 11a of theupper plate 11 is in contact with theglass plate 2 of thework 20, and air is evacuated through thegrooves 11b of theupper plate 11, whereby thework 20 is held against thelower surface 11a (FIG. 3(b)). Then, theupper plate 11 holding thework 20 is moved to a position above theupper surface 4a of thelower plate 4 by the robot arm 16 (FIG. 3(c)). Then, therobot arm 16 is moved downward until thewafer 1 is in contact with theupper surface 4a of thelower plate 4, and air is evacuated through thegrooves 4b of thelower plate 4, whereby thework 20 is held against theupper surface 4a of thelower plate 4. Shock applied to thelower plate 4 when thework 20 is mounted on theupper surface 4a is reduced by the elasticity of thesprings 8. Thereafter, thework 20 is heated by thecartridge heaters 6 and 13 embedded in the lower andupper plates 4 and 11, respectively, to soften thewax 209 between thewafer 1 and theglass plate 2. Thereafter, therobot arm 16 is moved upward while rotating or turning theupper plate 11, whereby theglass plate 2 is separated from thewafer 1.

According to the first embodiment of the present invention, after thewax 209 is softened by theheaters 6 and 13, therobot arm 16 moves theupper plate 11 upward while rotating or turning theupper plate 11, whereby theglass plate 2 is favorably separated from thewafer 1 with no flaw and no cracking of the wafer. Therefore, breakage of the wafer due to a flaw or cracking is avoided, so that the production yield is increased, resulting in a reduction in the cost of the device.

Further, since theupper plate 11 is supported and controlled by therobot arm 16, the rotation and the upward move of theupper plate 11 to separate theglass plate 2 from thewafer 1 is easily carried out, whereby automation of the apparatus is easily realized.

Further, since shock generated by theupper plate 11 when thework 20 is mounted on thelower plate 4 is absorbed by the elasticity of thesprings 8, thewafer 1 is prevented from cracking.

While in the above-described first embodiment theupper plate 11 is rotated or turned to facilitate separation between thewafer 1 and theglass plate 2, the rotation and the turning may be combined.

While in the above-described first embodiment therobot arm 16 is moved upward while rotating or turning theupper plate 11, it may be moved upward after weakening of the bonding strength between thewafer 1 and theglass plate 2 by rotating or turning theupper plate 11.

FIG. 4 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a second embodiment of the present invention. FIG. 5 is a perspective view illustrating a glass plate holding mechanism included in the apparatus of FIG. 4. FIGS. 6(a) and 6(b) are sectional views for explaining the operation of the mechanism.

As shown in FIG. 4, theupper plate 11 includes a pair of glassplate holding members 21 for holding theglass plate 2 at two locations on the periphery of the glass plate. As shown in FIG. 5, each glassplate holding member 21 comprises aclaw 21a for pressing theglass plate 2 to thelower surface 11a of theupper plate 11, and anair cylinder 21b having acylinder pin 21e pivotally connected operating point of theclaw 21a. Theair cylinder 21b and theclaw 21a are pivotally fixed to theupper plate 11 by afirst axle 21d and asecond axle 21d, respectively.

A description is given of the operation.

When thework 20 is not held against thesurface 11a of theupper plate 11, thecylinder pin 21e protrudes from theair cylinder 21b, and theclaw 21a that is pivotally connected to thecylinder pin 21e is turned outward on thesecond axle 21d (FIG. 6(a)). When thework 20 is held against thesurface 11a of theupper plate 11, theair cylinder 21b operates so that theclaw 21a is pulled by thecylinder pin 21a, whereby theclaw 21a is turned toward thework 20 on thesecond axis 21d (FIG. 6(b)). In this way, theglass plate 2 of thework 20 is pressed against thelower surface 11a of theupper plate 11 by theclaws 21a. Thereafter, as in the first embodiment, thework 20 is mounted on thelower plate 4. After heating of thework 20 to soften thewax 209, theupper plate 11 is moved upward to separate theglass plate 2 from thewafer 1. Since theclaws 21a hold theglass plate 2 at the edge, the edge of theglass plate 2 is bent when theupper plate 11 moves upward, and theglass plate 2 is slowly peeled from the periphery of thewafer 1, whereby the separation is facilitated.

FIG. 7 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a third embodiment of the present invention. In this third embodiment, aweight 31 is connected to the lower surface of thelower plate 4 to pull thelower plate 4 downward in the vertical direction. Theweight 31 must be heavy enough to maintain the attraction between theupper plate 11 and theglass plate 2 and the attraction between thelower plate 4 and thewafer 1 when therobot arm 16 pulls up theupper plate 11. The lower end of thespring 8 is fixed to thecylindrical holder 9. Since theupper end 8a of thespring 8 is not fixed to thelower plate 4, when the upper andlower plates 11 and 4 are pulled up, theupper end 8a of thespring 8 separates from thelower plate 4. That is, the tension of thespring 8 is not applied to thelower plate 4.

As described above, in this third embodiment, the rising speed of therobot arm 16 is suppressed by theweight 31 fixed to the lower surface of thelower plate 4. Therefore, even if a robot arm moving at a rate of 0.1 mm/sec. is employed, a precisely-controlled upward movement of therobot arm 16 is possible, whereby the separation between theglass plate 2 and thewafer 1 is carried out smoothly even if thewax 209 is not softened enough.

FIG. 8 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a fourth embodiment of the present invention. In this fourth embodiment, anair cylinder 41 is employed in place of theweight 31 of the third embodiment. Theair cylinder 41 is disposed on thebase 10, and thecylinder pin 41a is fixed to the lower surface of thelower plate 4.

In this structure, since thelower plate 4 is pulled downward by theair cylinder 41, it is possible to move thelower plate 4 downward according to the upward movement of therobot arm 16, whereby the separation between thewafer 1 and theglass plate 2 is carried out with higher stability compared to the third embodiment.

FIG. 9 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a fifth embodiment of the present invention. In this fifth embodiment, anupper end 51a of thespring 51 is fixed to the rear surface of thelower plate 4 and alower end 51b of thespring 51 is fixed to thecylindrical holder 9, whereby the resiliency of thespring 51 is used as the lower plate pulling means, in place of theweight 31 of the third embodiment.

In this structure, when the upper andlower plates 11 and 4 are moved upward by therobot arm 16, the resiliency of thespring 51 acts on thelower plate 4 as a tensile force, whereby the separation between theglass plate 2 and thewafer 1 is carried out with high stability.

FIG. 10(a) is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a sixth embodiment of the present invention, and FIG. 10(b) is a sectional illustrating a part of the apparatus shown in FIG. 10. In this sixth embodiment, anupper plate 61 has aconvex surface 61a against which theglass plate 2 is held. The curvature of theconvex surface 61a is in a range from several tens of microns to several hundreds of microns.

In this structure, after thework 20 is mounted on the lower plate 4 (FIG. 10(a)), the peripheral portion of theglass plate 2 is held against theconvex surface 61a of the upper plate 61 (FIG. 10(b)). Therefore, when theupper plate 61 is moved upward by therobot arm 16, theglass plate 2 is gradually peeled from the periphery of thewafer 1, realizing a stable separation.

FIG. 11(a) is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a seventh embodiment of the present invention, and FIG. 11(b) is a sectional view illustrating a part of the apparatus in the vicinity of an upper plate. In this seventh embodiment, anupper plate 73 comprises alower layer 71 comprising a material having a relatively large thermal expansion coefficient, such as brass, and anupper layer 72 comprising a material having a relatively small thermal expansion coefficient, such as invar.

In this structure, when theupper plate 73 is heated by thecartridge heater 13 to soften thewax 209, theupper plate 73 curves outwards due to a difference in thermal expansion coefficients between the upper andlower layers 72 and 71, providing a convex surface on thelower layer 71 against which theglass plate 2 is held. The curvature of the convex surface is in a range from several tens of microns to several hundreds of microns. Also in this case, the same effects as described in the sixth embodiment are achieved.

While in the above-described seventh embodiment theupper plate 73 comprises upper andlower layers 72 and 71 having different thermal expansion coefficients, theupper plate 73 or thelower layer 71 may comprise shape memory alloys which curve convexly when heat is applied.

FIG. 12 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with an eighth embodiment of the present invention. FIGS. 13(a) and 13(b) are perspective views illustrating an upper plate employed in this apparatus. In this eighth embodiment, anupper plate 84 shown in FIG. 13(a) is employed in place of theupper plate 73 of the above-described seventh embodiment. Theupper plate 84 is produced by cutting theupper plate 73 of the seventh embodiment into a plurality of small pieces in a direction perpendicular to the flat surface of theplate 73 at equal intervals and recombining these small pieces via insulating layers 83. The materials of the upper andlower layers 82 and 81 having different thermal expansion coefficients are the same as those employed in the seventh embodiment. A sheet heater, such as a rubber heater, is employed as theupper heater 85.

In this structure, since the curvature of theupper plate 84 due to the difference in thermal expansion coefficients between the upper andlower layers 82 and 81 is encouraged in the longitudinal direction of the small pieces of the upper plate, the surface of thelower layer 81 against which theglass plate 2 is held is convexly curved as shown in FIG. 13(b). Also in this embodiment, the same effects as described in the sixth embodiment are achieved.

FIG. 14 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a ninth embodiment of the present invention. FIG. 15(a) is a perspective view of an upper plate included in the apparatus of FIG. 14, and FIGS. 15(b) and 15(c) are sectional views taken alongline 15--15 of FIG. 15(a) for explaining the operation of the upper plate. In this ninth embodiment, the upper plate comprises acentral disc part 93 and a peripheralannular part 94. An end of thesupport shaft 14 is fixed to the center of the upper surface of thedisc part 93 while the other end is connected to therobot arm 16 via thecoupling 15. A pair ofcylinders 92, each having acylinder pin 92a, are disposed on the upper surface of theannular part 94 at opposite sides of thesupport shaft 14. Thesecylinders 92 are supported by acylinder fixture 91 which is fixed to thesupport shaft 14.Reference numerals 95 and 96 designate sheet heaters.

A description is give of the operation.

As shown in FIG. 15(b), when theglass plate 2 of the work is held against the lower surface of the upper plate, thecentral disc part 93 and the peripheralannular part 94 of the upper plate are on the same level. Then, thewax 209 is softened by thesheet heaters 95 and 96 and thecartridge heater 6. Thereafter, only the peripheralannular part 94 is moved upward by theair cylinders 92, whereby the peripheral portion of theglass plate 2 is bent upward as shown in FIG. 15(c). Also in this embodiment, since the separation of theglass plate 2 starts from the periphery of thewafer 1, the same effects as described in the sixth embodiment are achieved.

While in the above-described ninth embodiment the upper plate comprises two parts, i.e., thecentral disc part 93 and the peripheralannular part 94, it may comprise three parts or more, i.e., a central disc part and a plurality of peripheral annular parts.

FIG. 16 is a sectional view illustrating an apparatus for separating a wafer from a glass plate in accordance with a tenth embodiment of the present invention. In this tenth embodiment, the apparatus according to the first embodiment includes anozzle 101 for applying asolution 102 that dissolves an adhesive, such as wax, to the boundary between thewafer 1 and theglass plate 2. Preferably, SOLFIN-TM (trademark of TOKUYAMA PETROCHEMICAL CO., LTD.) is employed as thesolution 102.

In this structure, since the wax connecting thewafer 1 and theglass plate 2 is gradually dissolved by applying thesolution 102 to the boundary between them, the adhesion of the wax is reduced, whereby the subsequent separation process using therobot arm 16 is facilitated. In addition, it is possible to remove the wax before the separation process.

If thenozzle 101 is movable in the vertical direction, it is possible to apply thesolution 102 during the separation process using therobot arm 16. That is, even when thelower plate 4 is moved upward by therobot arm 16 and the boundary between thewafer 1 and theglass plate 2 is moved upward, thesolution 102 can be applied to the boundary, whereby the time required for the separation process is reduced.

Thenozzle 101 may be included in the apparatus according to the above-described second to tenth embodiments of the present invention. In this case, the separation between the wafer and the glass plate is further facilitated.

FIG. 17 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with an eleventh embodiment of the present invention. In this eleventh embodiment, the apparatus according to the first embodiment shown in FIG. 1 is disposed in acontainer 111 filled with thesolution 102. Aheater 115 for heating thesolution 102 is buried in a part of thecontainer 111.

In this structure, thesolution 102 heated by the buriedheater 115 permeates into thewax 209 connecting thewafer 1 and theglass plate 2 and dissolves thewax 209, whereby the separation is carried out with high reliability.

FIG. 18 is a sectional view illustrating an apparatus for separating a wafer from a support plate in accordance with a twelfth embodiment of the present invention. In this twelfth embodiment, the apparatus according to the first embodiment shown in FIG. 1 is hermetically sealed in acontainer 111a, and an inert gas, such as N₂, is introduced into thecontainer 111a to a prescribed pressure using avalve 113 and apressure gauge 114.

In this structure, since the pressure in thecontainer 111a is increased, the permeation of thesolution 102 into the wax connecting the wafer and the glass plate is increased, whereby the separation process is smoothly carried out.

Claims (19)

What is claimed is:

1. An apparatus for separating a wafer from a support plate attached to the wafer with a thermally softened adhesive, the wafer and support plate constituting a work having opposite first and second surfaces, the apparatus comprising:

an upper plate having opposite upper and lower surfaces and a plurality of holes at the lower surface through which air is evacuated to hold the first surface of the work to the lower surface;

a lower plate having opposite upper and lower surfaces and a plurality of holes at the upper surface through which air is evacuated to hold the second surface of the work to the upper surface;

a heater for softening the thermally softened adhesive embedded in at least one of the upper and lower plates;

a robot arm for moving the upper plate in vertical and horizontal directions; and

a shaft rotatably connecting the upper plate to the robot arm.

2. The apparatus of claim 1 comprising means for absorbing shock generated when the work held against the lower surface of the upper plate is put in contact against the upper surface of the lower plate, said shock absorbing means being disposed beneath the lower plate.

3. The apparatus of claim 2 wherein said shock absorbing means comprises:

a plurality of rods fixed to the lower surface of the lower plate at right angles;

a plurality of cylindrical holders disposed beneath the lower plate in which respective rods are movably inserted in a vertical direction; and

a plurality of springs disposed between the lower plate and the respective cylindrical holders.

4. The apparatus of claim 1 comprising means for holding the support plate to the lower surface of the upper plate by pressing the support plate against the lower surface of the upper plate, said means being disposed at a periphery of the upper plate.

5. The apparatus of claim 4 wherein said support plate holding means comprises:

at least two air cylinders fixed to the periphery of the upper plate; and

claws connected to the respective cylinders for holding the peripheral portion of the support plate on the lower surface of the upper plate.

6. The apparatus of claim 1 comprising means for pulling the lower plate downward in the vertical direction disposed on the lower surface of the lower plate.

7. The apparatus of claim 6 wherein said lower plate pulling means is a weight fixed to the lower surface of the lower plate.

8. The apparatus of claim 6 wherein said lower plate pulling means is an air cylinder connected to the lower surface of the lower plate.

9. The apparatus of claim 6 wherein said lower plate pulling means comprises:

a plurality of rods fixed to the lower surface of the lower plate at right angles;

a plurality of cylindrical holders disposed beneath the lower plate, in which the respective rods are inserted movably in vertical direction; and

a plurality of springs disposed between the lower plate and the respective cylindrical holders, each spring having opposite ends respectively fixed to the lower plate and the cylindrical holder.

10. The apparatus of claim 1 wherein said upper plate has a convex lower surface.

11. The apparatus of claim 1 wherein said upper plate comprises a first layer having a surface for contacting a work and a second layer disposed on the first layer, and the first layer has a thermal expansion coefficient larger than that of the second layer.

12. The apparatus of claim 11 wherein the upper plate comprising the first and second layers is divided into a plurality of parts having the same width in a direction perpendicular to the upper plate, and a heat insulating material is interposed between the adjacent parts.

13. The apparatus of claim 1 wherein said upper plate comprises a shape memory alloy which deforms when heated so that the upper plate has a convex lower surface.

14. The apparatus of claim 1 wherein said upper plate comprises a central disc part fixed to the shaft, and a peripheral annular part surrounding the disc part and moving in the vertical direction.

15. The apparatus of claim 1 comprising a nozzle for applying a solution that dissolves the thermally softened adhesive to the wafer and the support plate.

16. The apparatus of claim 1 comprising a container containing the apparatus and filled with a solution that dissolves the thermally softened adhesive.

17. The apparatus of claim 16 wherein said container is hermetically sealed for applying pressure to the solution in the container.

18. The apparatus of claim 16 comprising a heater for heating the solution.

19. The apparatus of claim 17 comprising a heater for heating the solution.

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